Lecture 3 Flashcards
0
Q
Absoprtion
A
Small molecules move frim walls of GI into circulation
1
Q
Digestion
A
Food is broken down into small molecules
- barrier and immune function
2
Q
Transport
A
In circulation and to cells
3
Q
Metabolism
A
In the cell, the chemical reactions that occur to molecules so they can be utilized
4
Q
Why do we eat?
A
- hunger
- appetite
5
Q
Hunger
A
A physiological process that prompts us to find and eat food
6
Q
Appetite
A
A psychological desire to eat specific foods, from environmental stimulu
- smell, sight, sound ( marketing and presentation of food)
- social cues: certain location/activities, feelings
7
Q
Satiety
A
The feeling of being full
8
Q
What prompts hunger and satiety?
A
- signal to the hypothalamus
• nerve cells/stretch receptors
• hormones - food bulk: bulk (fiber and water), protein and fat, and eating slowly can promote satiety
9
Q
Hormones that promote hunger and satiety
A
- low blood glucose levels trigger glucagon (signals hunger)
- ghrelin (signals hunger)
- Cholecystokinin (signals satiety)
10
Q
Ancillary organs
A
- pancreas
- liver
- gallbladder
11
Q
Mechanical digestion
A
Muscle action and movement
12
Q
Chemical digestion
A
Reaction and secretion
- hydrolysis: break down of compounds with the addition of water
- enzymes: proteins that speed up chemical reaction, unchanging in the process (-ase)
- hormones: chemical messengers that travel to target cells, which then carry out a targeted response
13
Q
Saliva contains…
A
- mucus: that lubricates and moistens food
- antibodies and lysozyme (enzyme): defend against bacteria
- chemicsl digestion: amylase to break down starch
14
Q
Esophagus
A
- anatomy
• connects mouth and stomach: 10 inches long
• epiglottis: prevents food from getting lodged in trachea
-muscle action: peristalsis and gravity - passes lower esophageal sphincter into the stomach
15
Q
Stomach anatomy
A
- empty is about 3/4 of a cup large
- reservoir that can hold up to about 4 cups
16
Q
Stomach: muscle action
A
-peristalsis
-mechanical digestion by miscle layers: grinds, churns, mixes
-chyme: semiliquid mass mixed with gastric secretions
• chyme leaves stomach via phyloric sphincter 1-4 hrs after eating
17
Q
Stomach secretion: gastic juice
A
- HCl
- pepsinogen/pepsin
- gastric lipase
- intrinsic factor
18
Q
HCl
A
- release stimulated by the hormone gastrin
- denatures protein- chemical digestion
- kills bacteria
- activates enzymes
19
Q
Pepsinogen
A
- inactive protein enzyme
- activated to pepsin (active pepsin enzyme) by HCl
- starts protein digestion -chemical digestion
20
Q
Gastric lipase
A
- fat digestion begins, small amount occurs - chemical digestion
21
Q
Intrinsic factor (IF)
A
Protein needed for absorbtion of vitamin B12
22
Q
GI Problems: gastro-esophageal reflux disease (GERD)
A
- weakened LES
- some contributors: smoking, overweight large high fat meals, spicy, and acidic foods, caffeine, chocolate, alcohol, lying down after a meal
- treatment: diet, antacids, other drugs to reduce HCl production
23
Q
Segmentation
A
A muscle movement action that helps movement of food in the small intestine
- churning and mixing and moving the food up and down as well so its well mixed
24
Small intestine: anatomy
- food stays 3-10 hrs in SI
- duodenum: 1'
• connected to stomach via pyloric sphincter
- jejunum: 4-5'
- Ileum: 4-5'
• connected to large intestine via ileocecal valve
- very folded interior
25
Small intestine: muscle action
Peristalsis and segmentation
26
Where is nutrients absorbed the most in thr small intestine??
Duodenum and jejunum
27
Small intestine secretions
- secretions received from:
• pancreas, gallbladder and liver, intestinal cells
- hormones secretred from small intestine to target organs
28
Pancreas makes ______ for digestion
- bicarbonate: nuetralize contents, enzymes can function
| - enzymes: amylase, protease, lipase
29
Liver makes _____ for digestion.
Produces bile, an emulsifier for fat ansorption
| - other major nutrient related jobs too
30
The gallbladder stores ____ for digestion
Stores and secretes bile
31
Intestinal cell enzyme secretions
- cells of the SI produce brush border enzymes
• specific protease
• lipase
• specific sugar enzymes (sucrase, maltase, lactase)
32
Secretin signals....
- the stomach to slow gastric emptying
| - the pancreas to secrete panceatic bucarbonate
33
Chilecystokinin (CCK) signals...
- the gallbladder to release bile
- the pancrease to release pancreatic enzymes
- the stomach to slow gastric emptying
- satiety
34
Gastric inhibitory peptide(GIP) signals...
- the stomach ti slow gastric emptying
| - the pancreas to increase insulin release
35
Large intestine/ colon
- undigested/ unabsorbed matter passes through ileocecal valve to the large intestine
• water, undigested/ unabsorbed residues - fibers, sloughed cells, bacteria, non-food items
36
Bacteria in the large intestine/colon
- 90 trillion bacterial cells
- finish digestion and make
• short chain fatty acids- used by colon cells
• vitamin K
• B12 that the bacteria use- not absorbed
• gas
- prebiotics: feed the bateria
- probiotics: replace the bacteria
37
Large intestine: muscle action and movement
Peristalsis
- food may stay in LI FOR 12-24 hrs
38
Absorption
- absorption: passing of nutrients from thr GI tract into circulation
- most absorption occurs in thr SI
• stomach: some water, alcohol, fluoride
• large intestine: water, short chain fatty acid, vit K
- SI: heavily folded tissue called mucosal membrane
• 500x increase surface area = increase absoption
• within folds fingerlike projections called villi
• villi contains absoprtive cells called enterocytes
• each enterocytes contain microvilli (brush border)
39
Passive/simple diffusion
Solutes travel from a high to a low concentration
40
Facilitated diffusion
Carrier protein facilitates, high to low
41
Active transport
Carrier protein and energy, solutes can travel from a low to a high concentration
42
Endocytosis (pinocytosis)
Active transport by which a small amount of intestinal contents is engulfed by the cell membrane into the cell
43
SI into circulation: nutrieny transport
- nutrients travel to the blood or lymph for distribution to other cells
- each villus contains capillaries (smallest blood vessel) and lacteal (lymph vessel)
- nutrients cross over into these system
44
Nutrient transport: Cardiovascular system
- nutrients cross over into capillaries in villa ---> hepatic portal vein ---> to the liver for storage, utilization or back into curculation
- water-soluble nutrients (protein, carb, some vits, small fatty acids)
45
Nutrient transport: lymphatic system
- nutrients cross into lacteals in villi ---> transported to larger lymph vessels ---> drains into circulation by the heart ---> the curculation and liver
- larger fat soluble nutrients
46
Metabolism
- the sum of all chemical processes involved in maintaining life
47
Anabolism
Build up molecules and use energy
48
Catabolism
Break down molecules and release energy
